1. Field of the Invention
The present invention generally relates to industrial robots and the fixtures and carrier assemblies used to route various supply lines along the moving members of a robot. More specifically, this invention relates to a dress bar with which fluid, air and/or current conducting lines can be routed on a robot to a tool mounted to the robot's wrist, wherein the fluid, air and/or current conducting lines can be routed through the dress bar so as to be protected from the operating environment of the robot, and such that installation, maintenance and service of the lines are simplified.
2. Description of the Prior Art
Industrial robots are widely employed for transferring workpieces between work stations and successive operations, to perform work at specific stations, and to manipulate tooling at work stations to obtain the proper tooling orientation for a particular operation. Their high reliability, precision, relatively low cost, and ability to be reprogrammed to tailor their operation to changing work conditions have resulted in robots being highly valued equipment for high volume manufacturing processes, such as in the automotive industry.
Among the many specific operations in which robots are employed, robots have found wide use in welding operations such as arc and spot welding. Such applications are generally unique for their requirement that the welding tool must be supplied with electrical power, a cooling fluid such as water, air or an inert gas to provide a proper welding atmosphere, a control signal to regulate the operation of the tool, and current for generating an electric arc or spot weld between the tool's electrode and a workpiece. In the past, the supply lines that carry the fluid, gas and electric power were often routed from a fixed location above or adjacent the robot, but only if the robot had a sufficiently limited work envelope. An example of this approach is taught by U.S. Pat. No. 4,582,281 to Van Camp, in which a flexible support and carrier assembly is used to physically support hoses and leads, as well as route the hoses and leads from a base adjacent the robot to a welding gun manipulated by a robot.
While such an approach may be adequate for welding robots having a relatively limited work envelope, for highly articulated robots and those having a large range of movement, the supply lines must typically be routed along the moving members of the robot arms, linkages and wrist. Under such circumstances, proper attention must be given to routing the supply lines along the moving members of the robot in order to ensure that they will not become tangled, snagged, pinched, cut, pulled or abraded during the operation of the robot.
Consequently, the prior art has also suggested various methods and fixturing for routing supply lines along the moving members of a robot, a process known as "dressing out a robot." One example is taught by U.S. Pat. No. 4,904,148 to Larsson, in which a flexible conduit composed of a number of supply lines is routed within the moving members of a robot. While such an approach is able to protect the supply lines from the working environment of the robot, such a technique complicates assembly of the robot and installation of the supply lines, and greatly impedes the ability to maintain and repair the supply line in the event of a failure.
A more conventional solution is taught by U.S. Pat. No. 4,705,243 to Hartmann et al., which teaches a technique for routing a bundle of hoses and leads along the exterior of the robot. The particular teachings of Hartmann et al. are directed to the use of casings which pivotably support the bundle at each axis of rotation of the robot. The casings are configured with a number of bores in which the individual hoses and leads are received and secured. The rotatable mounting of the casings enables the hoses and leads to rotate sufficiently to prevent them from being excessively bent during the operation of the robot.
While the teachings of Hartmann et al. provide certain advantages over the prior art, certain other disadvantages exist. For example, the bundle of hoses and leads is still exposed to the working environment of the robot, and is therefore vulnerable to being damaged by surrounding equipment, tooling or workpieces during operation, or from accidents that may occur during the setup and maintenance of the robot. The large bundle of loops that drape downwardly from the robot are particularly vulnerable to damage. Secondly, any damage to a hose or lead necessitates that the entire length of hose or lead be removed from the robot, which can often be in excess of ten meters. Therefore, there exists a significant potential for damage to a hose or lead, which directly causes production downtime and/or poor weld quality, and eventually necessitates the replacement of the entire length of damaged supply line.
From the above discussion, it can be readily appreciated that the prior art does not disclose a technique or the necessary equipment for routing the supply lines of an arc or spot weld robot in such a manner that the supply lines are protected from the robot's working environment, while simultaneously being configured to facilitate maintenance and repair of the robot and its supply lines. Accordingly, what is needed is a device for supporting one or more hoses and/or lines along the moving members of a robot, wherein the support device can be readily mounted on a robot, serves to protect the hoses and lines from the working environment of the robot, and facilitates the repair and maintenance of the robot by permitting ready access to the hoses and lines and by enabling the removal of a limited section of damaged hose or line.